Truing device for grinding wheels



NOV. 6, 1934. J E R 1,979,536

TRUING DEVICE FOR GRINDING WHEELS Filed Feb. 28, 1929 7 Sheets-Sheet 1Nov. 6, 1934. J. EDGAR TRUINGDEVI CE FOR GRINDING WHEELS Filed Feb. 28,1929 Sheets-She'et 2 Nov. 6, 1934. I .1. EDGAR TRUING DEVICE FORGRINDING WHEELS Filed Feb. 28, 1929- 7 Sheets-Sheet 3 Nw J m I I n mwm$m 4 ig Q Joizfi i727 ar y WP Nov. 6, 1934 EDGAR 1,979,536

TRUING DEVICE FOR GRINDING WHEELS Filed Feb. 28 ,1 1929 '7 Sheets-Sheet4 Fig.7:

Fig. 8.

' INVENTOR I John Edgar ATTORNEYS Nov. 6, i934. J, EDGAR 1,979,53

TRUING DEVICE FOR GRINDING WHEELS John Edgar ATTORNEYS Nov. 6, 1934. rJ. EDGAR 7 1,979,536

TRUING DEVICE FOR GRINDING WHEELS FiledFb. 28/1929 7 Sheets-Sheet 7 IPatented Nov. 6, 1934 UNITED STATES TRUING DEVICE non GRINDING, WHEELSJohn Edgar, Rockford,

111., assignor to Barber- Oolman Company, Rockford, 111., a corporationof Illinois Application February 28, 1929, Serial No. 343,451

29 Claims.

This invention relates to a method for making form tools and novelmechanism embodying work supporting and grinding means and means forguiding a. tool or other device in straight, curved 5 and modified pathsparticularly adapted for employment in the manufacture of such formtools. This application is a continuation in part. of applicant'scopending application Serial No. 80,471 filed January 11, 1926.

There are two principal methods commonly used in the manufacture of formtools, the older of which is the so-called master or fly-tool method. Toproduce a form tool by this method, it is necessary to make, first, amaster or. fly- 1 tool which possesses the shape that is desired.

to be produced by the form tool, but since this fly-tool is made from apiece of unhardened metal and is hardened after being properly shaped,any hardening distortion must be removed by a manual 'process such asstoning. This method hasmany disadvantageous features besides beingcostly.

In view of this, another method has been advanced whereby form tools areground from hardened pieces of metal by means of abrasive wheels shapedto the proper contour. To correctly shape such an abrasive wheel it hasbeen the custom to employ a templet to which the wheel was trued, theform of the templet not being a duplicate of the form desired butcorresponding to the form desired as corrected to compensate for theclearance angle with which the tool is made, undercut and side clearanceor any of them as may be desired on form tools for making straight gash.or spiral gash cutters. It results, therefor, as will be more fullydescribed hereinafter, that to make a form tool adapted to produce acircuit sectionv it is necessary that the contour of the abrasive wheelused be ellipti-.

- cal, it end clearance alone is to be compensated for, and the contourof the abrasive wheel must be further modified to compensate for theother factors.

It is an object of the present invention to provide a new, improved andsimplified truing device for grinding wheels adapted for use in makingform tools, and arranged to dress the wheel not only to compensate forthe end clearance angle but also to compensate for undercut and sideclearance as may be desired on form tools for making straight gash orspiral gash'cutters Another object is to provide a novel mechanismwhereby a dressing device may be moved through modified circular pathswithout the need 0! extensive mathematical computations or the use oftemplets.

Another object is to provide an adjustable mechanism having means forsupporting a truing device for abrasive wheels and embodying means forguiding said device through'the curve of the proper ellipse upon themechanism being adjusted in accordance with the radius of the circularform desired to be produced by the form tool.

Another objectis to provide such a mechanism embodying readilyadjustable means for compensating for undercut and spiral angle.

Further objects and advantages of the invention will become apparent asthe description proceeds.

In the drawings:

Fig. 1 is a front elevation of a machine embodying the'preferred form ofthe invention.

Fig. 1ais a diagrammatic view of a form tool and a grinding wheeladapted to move at a clearonce angle with the plane perpendicular to thecutting surface of the tool.

Fig. 2 is a side elevation looking at the left hand side of Fig. 1.

Fig. 3 is a fragmental section through the table, work support and toolsupport, taken in the plane of line 3-3 of Fig. 2.

Fig. 4 is a view along the line 4-4 of Fig. 3.

. Fig. 5' is a view along the line 5--5 of Fig. 3.

Fig. 6 is a similar view with the tool holder in a different position.

Fig. 7 is a view along the line 7-7 of Fig. 3.

Fig. 8 is a fragmentary plan view of the undercut control shown alongthe line 88 of Fig. 3.

Fig. 9 is airont elevation of the, mechanism for mounting the toolblank.

Fig. 10 is a plan view thereof.

Fig. 11 is a vertical section along the line 11-11 of Fig. 12.

Fig: 12 is a section along the inclined line 12-12 of Fig. 9. I

Fig. 13 is a section along the line 1313 of Fig. 11. 7

Figs. 14 to 18 are diagrammatic, views exempliiying a practicalapplication of the preferred embodiment of the invention in dressinggrinding wheels and shaping a form tool.

While my invention is susceptible of embodiment in many different forms,I have shown in the drawings and will herein describe in detail 5 onesuch embodiment, with the understanding that the present disclosure isto be considered as an exem'plification of the principles of theinvention and is not intended to the invention 00 the embodimentillustrated. The scope of the 110 invention will be pointed out in theappended claims.

As illustrated in the drawings the invention in its exemplary embodimentis disclosed in connection with a grinding machine comprising a bed orbase 1 having a column 2 formed integrally therewith and extendingupwardly from the rear portion thereof. A spindle head 3 is slidablymounted on the column and has an arbor or spindle 4 rotatably mountedthereon and extending forwardly from the face of the column and over aplaten or table 6 which is movable transversely of the spindle above theknee portion 8 of the machine base. Preferably a saddle 7 is interposedbetween the knee and the table, which saddle is adjustablelongitudinally of the spindle 4 on ways 9 by means including a manuallyoperable hand wheel 10. The table 6 is slidable on the saddletransversely of the spindle on ways 11 by means including a manuallyoperable hand wheel 12. The hand wheel 12 may be secured to one end of ashaft 13 (Fig. 1) the other end of which may have a pinion and rackconnection (not shown) with the table. The spindle head 3 is adjustablevertically by means including a hand wheel 16 (Figs. 1 and 2) which handwheel drives through a micrometer device (designated generally as 1'7),and suitable gearing intermediate said micrometer device and the spindlehead (not shown). Said micrometer device, the function of which will bemore fully explained hereinafter may be of any suitable form andpreferably of the type shown in my copending application Serial No.377,391 filed July 11, 1929, and issued as Patent No. 1,760,938 on June3, 1930. g

The construction of the machine thus far described (with the exceptionof the micrometer device 17 referred to in said patent), is well knownto those skilled in the art, the spindle 4 being generally driven from amotor 18 in the base of the machine by means of a belt 19, which beltengages a pulley 20 on the spindle shaft and suitable idler pulleys 21and 22 for permitting vertical adjustment of the head on the column.

The invention contemplates that a dressing mechanism A will be mountedon one end of the table 6 and that a tool blank or work holder B will bemounted on a work support 23 slidably mounted on the left hand portionof the table so that by manipulating the hand wheel 12 to move the table6, a dressing tool 24 may be moved into and out of operative relation tothe grinding wheel W and when the dressing tool has been moved into aninoperative position a tool blank 25 mounted in the work holder B may bereciprocated transversely of the grinding wheel axis for grinding theblank to the contour which has been formed on the wheel W- by thedressing tool. The work holder B will be more fully describedhereinafter. Attention will now be directed towards the dressingmechanism generally designated A.

When grinding form tools it is necessary to make allowance not only forthe end clearance angle to which the tool is ground, but in addition itis sometimes desirable when grinding straight gash tools to provide forundercut or side clearance or both and when grinding spiral gash toolsto provide for the spiral, for undercut and for side clearance. Theinvention contemplates that the dressing mechanism A will embody devicesoperating on the same principle as that disclosed in the hereinbeforementioned prior application for compensating for the end clearance angleand that it will embody devices adapted to modify. the path ofthedressing tool 24 to compensate for side clearance, undercut andspiral angle and that the tool blank 25 will be positionable by means ofthe work holder B to be ground to the desired end clearance angle andfor side clearance.

In Fig. 1a the form tool 25 is shown diagrammatically in operativerelation with a grinding Wheel, the tool being presented to the grindingwheel to provide the tool with an end clearance of angle a. It will beapparent that if the dimension :1: represents the depth or radius of thecut desired to be reproduced by the tool, it will be necessary to makethe depth y measured perpendicular to the clearance end of the toolslightly less than the depth 2: because of the angular position of thetool during grinding, the dimension 11 being equal to x multiplied bythe cosine of the angle a. In other words, the contour to be ground onthe tool will be that of an ellipse which ellipse is the projection on avertical plane of the inclined semi-circle of radius a: which definesthe cutting edge of the tool.

Thus, the angle a is a clearance angle. A clearance angle may be definedas the angle of recession of the surface of a tool back of its cuttingedge relative to a line through said edge extending in the direction ofmovement of the tool relative to the work. If the recession is on theend of the tool, as in the present instance, it has end clearance; if onthe side, it has side clearance.

The invention contemplates a holder 26 (Figs. 1 and 3). for the dressingtool 24 which holder is freely movable and constrained to move in avertical plane, together with a head mounted for movement on an axisinclined at the end clearance angle with the horizontal, a connectionbetween the tool holder and the head such that when the head is turnedon its inclined axis,

, the tool holder 26 will be moved through a curved path which is ahorizontal projection of the path of the head, and means to modify thepath of the dressing tool to compensate for side clearance, undercut andspiral angle as may be desired. The spiral angle of a form tool is theequivalent of the helical angle at the pitch line of the rotary cutterto be produced. In the form tool, this spiral angle is the angle ofinclination of the cutting face laterally of the tool. The undercut in aform tool is the angle of inclination of the cutting face longitudinallyof the tool. In the case of a rotary cutter, the undercut is the angularoffset of the cutting face from a radial plane through the cutter axis.The form tool for cutting a rotary cutter having an undercut face, mayitself haveno undercut, but in such instance has a form compensated forthe undercuton the cutter to be produced.

In each case of a spiral angle, an undercut, and/or a clearance angle,the effective contour of the grinding wheel on the work is foreshortenedin'some respect. This foreshortening is compensated for by so changingthe contour of the grinding wheel that theforeshortened or dis- Y.torted form which is applied to the work will be the desired form.

In the preferred embodiment of the invention as illustrated herein, thetool holder 26 (Figs. 1 and 3) is mounted on a shaft 27 which isjournaled on a horizontal axis on a slide 28 supported on a swinginghead or arm 29. The arm 29 is herein shown mounted swingably upon apivot 30 which is secured to an uprising portion 31 of the table 6. Theslide 28 is freely movable radiall y on the swinging arm or head 29 andis preferably mounted on ball bearings 28 (Fig. 4) so as to eliminatestatic and sliding friction. Thus the tool holder is freely movable .andis constrained to move in a vertical plane by the arm by means of theshaft 2'7.

The dressing mechanism comprises generally such means for supporting thetool'holder 26 and means for guiding and moving the tool holder throughthe desired paths. Thislast means, in the exemplary form illustrated inthe drawings, includes a support 32 slidable longitudinally on thetable-6. A side clearance control base 33 is pivoted, on said support 32and carries a frame 33 (see Figs. 3 and 8) on which an annular mem-, beror barrel 34 is rotatably mounted on an axis inclined at the endclearance angle with the horizontal. A cross slide 35 adjustably mountedwithin said barrel for movement transversely of its axis carries arotatably mounted sleeve 36 in which a shaft 3'7 is slidable axially. Ahead, guide or radius bar 38 (Fig. 4) on one end of said shaft hasa-universal connection 39, preferably of a ball and socket type, withthe shaft 2'7 on which the tool holder 26 is mounted.

To compensate for spiral angles and undercutting the opposite end of theshaft 3'7 carries a second radius bar 40 having a universal connection41 with a slide 42 movable radially on a swinging control arm 43 whichis pivoted on an inclined axis parallel to the shaft 3'7. The pivotalmounting for the arm comprises a pin 44 positioned in the upper end ofan adjustably mounted spiral angle control member 45, which member isangularly adjustable upon arcuate ways 46 (Figs. 3 and 8) about an axisperpendicular to the shaft 3'7. These ways are formed on an undercutcontrol member 47 which in turnis angularly adjustable about an axisperpendicular to the shaft 3'7 and to the axis of the ways 46, onarcuate ways 48' formed on a control support 49 mounted on the end ofthe frame 33..

The support 32 is slidably mounted upon the table 6 for movementtransversely of the p e 4 and is preferably mounted on the table bymeans of balls 32 or other anti-friction bearings so as to eliminate asfar as possible static friction. This provides a freely slidableperpendicular connection between the guiding and compensating means andthe tool holder 26 adapted to project onto the verticalplane of the toolholder, the curve through which the ball or joint 39 is moved whenpositioned radially outward of the axis of shaft 3'7. since the ball isconstrained to move in a plane parallel to that of the tool holder. Theside clearance control base 33 is pivotally mounted on the support 32 bymeans of a pivot pin 50 and an annular way 51. A protractor 52 (Fig. 8)is provided to determine the amount of side clearance by the position ofthe base 33, clamping bolts'53being adapted to secure the base'in itsadjusted position.

The frame 33 has a segmental Portion 33 mounted on an arcuate way 33 onthe base 33, and comprises a U-shaped end portion (Fig. 8) extending tothe right in the drawings from the segmental portion. The arcuate way 33is concentric with the shaft 3'7.

The frame 33' is also provided witharcuate ways 55 concentric with theshaft 3'7,which ways are arranged to support and guide the barrel 34,

the periphery of which is provided with a corresponding guide 56, Theperiphery of the barrel is also provided with worm wheel teeth 57 (Figs.1

and '7) engageable by a worm 5'7 on a manually operable shaft 58rotatably mounted in the base frame 33. v

The cross slide 35 is mounted on rectilinear ways 59. extendingtransversely of the barrel so that the shaft 3'7 may be moveddiametrically across the barrel. A cross feed screw 60 (-Figs. 1 and 3)is arranged to engage a nut 61 on the cross slide for adjusting thecross slide trans versely of the barrel and has a squared outer end 62for engagement by a suitable handle.

The sleeve 36 which is rotatably mounted on the cross slide 35 issuitably secured against longitudinal movement and may be rotated bymeans of a manually operable worm' 63 cn a shaft 63" (Figs. 1, 3 and 'l)which engages a worm wheel 64 secured to the sleeve and has squaredouter ends 65. The sleeve may be locked in its normal position by meansof .a spring operated plunger 66, The shaft 3'7 is freely slidablelongitudinally in i the sleeve 36 and may be secured against rotationcommon longitudinal plane through the shaft axis. J'he radius bar 38 atthe left hand end of the shaft (Fig. 3) has a slide '70 which isadjustable radially thereon and which may be secured in its radiallyadjusted pcsition by means of suitable clamping boltsJ'71 (Fig. 1). Thisslide '70 supports one member '72 of the universal joint 39, the othermember '73 of which is secured to the tool holder shaft 2'7. 1,10

The radius bar structure, swinging arm and slide on the right end of theshaft 37 (Figs. 1 and 3) may be duplicates of those shown for the lefthand end and just described. Thus the radius bar 40 is provided with aslide '74 adjustable radially thereon and adapted to be secured inadjusted position by means of bolts '75. This slide carries one member76 of the universal joint 41, the other member '77 of which is securedto a shaft '78 rotatably mounted on the slide 42 which is freely movableradially on the swinging arm 43. The swinging arm in this instance ismounted on the inclined pivot pin 44.

The. work support 23 is slidably mounted on the uprising portion 31 ofthe table 6 along ways 80 for movement transversely of the grindingwheel spindle 4 so that after the grinding wheel W has been properlydressed, the tool blank holder Bmay be traversed across the grindingwheel'without moving the table. This traverse movement may be impartedto the work support 23 manually by any suitable means, which meanspreferably includes a hand wheel 81 rotatably mounted on the tableportion 31 and readily aceessible to an operator standing in front ofthe machine.

The worksupport B, as disclosed herein, is

v adapted to support the tool blank 25 in any one of a number of desiredpositions for making form tools 'of various types as described morefully hereinafter. In its'exemplary form, this device comprises acircular base 100 rotatably mounted on the upper surface of the support23 by means of a pivot belt 110 and an annular guide ring 111. The guideringmay be adjusted angularly with respect to the support 23 asindicated on a scale 101 and may be secured in its adjusted position bymeans of the pivot bolt. A spring pressed plunger or index pin 112carried on the base 100 is adapted to engage either one of two sockets150 113 positioned 180 apart in the ring 111. Extending upwardly fromthe base 100 and formed integrally therewith are a pair of inclinedbrackets 114. A body member 115 is positioned intermediate said bracketsand pivotally mounted on a horizontal shaft 104 mounted in the brackets.As hereinafter more fully set forth said pivotal mounting is providedfor permitting modification of the end clearance angle to which the toolblank 25 is ground, the upper portion of the member 115 carryingclamping bolts 116 passing through slots 117 in the brackets 114 tosecure the body member in its adjusted position as determined b a scale118.

A centrally apertured disk 119 issecured to the body member 115 and isprovided with an annular T-slot 120 and a central boss 121. An angularlyadjustable member 122 has a shoulder engaging said boss and carries aplurality of bolts- 123 with their heads in said T-slot so that the head122 may be clamped in its adjusted position on the disk 119 asdetermined by an indicating scale 1-02. The head 122 is provided withrecti- 'linear guides 123 normally positioned horizonthereon by means ofa boss 127 on the cross slide and being adapted to be clamped in itsadjusted position, as determined by a scale 103, by means of a pluralityof bolts 128. Suitable means, such for example as a notch 129 andclamping bolt 130, may be provided for securing the tool blank 25 to thesupporting member 126.

The cross slide 124 may be adjusted on the guides 123 to displace thetool blank longitudinally of the grinding spindle 4 by means of a feedscrew 131 non-rotatably supported on the cross slide and engaged by anut 132 rotatably mounted on the head 122. This nut is provided with abevel pinion 133 which engages a second bevel pinion 134 mounted on oneend of a shaft 135. This shaft carries a worm wheel 136 which mesheswith a worm 137 on the shaft 104 so that by rotating the shaft, thecross slide may be actuated.

The shaft 135 preferably extends outwardly of the body member 115 tooperate a micrometer device designated generally 138 by which theposition of the cross slide may be indicated. The amount of thedisplacement of the tool blank by movement of the cross slide may bedetermined by the difference between the two readings on the micrometerdevice 138.

With all of the parts in their-normal or zero positions, that is withthe slides '10 and '14 cencentrally on the radius bars, the cross slide35 centrally of the barrel 34, the barrel with the cross slide wayshorizontal, and the spiral angle control support 45, the undercuttingangle control member 47, the side clearance control base 33 and theframe 33 in their central positions, rotation of the shaft 37 by meansof the sleeve 36 and worm shaft 63 will pivot the tool holder 26 withoutswinging the arms 29 or 42 or moving the slides 28 and 42, the dressingtool merely pivoting about an axis through its point. Protractors .orscales are preferably provided on the various parts to facilitate theiradjustment.

.As described hereinbefore, the dressing mechanism A and the tool blankor work holder B are generally constructed at a standard or desired endclearance angle, the dressing mechanism being so set to compensate forthe modified form indicating zero, holds the tool blank parallel to thetable 6 and perpendicular to the grinding wheel spindle. The dressingmechanism is also set at zero except to the angle of form. Thus theprotractors 90, 91 and 92 on the side clearance, spiral angle andundercutting controls respectively are at zero and the slides 70 and 74are central of the radius bars 38 and 40 respectively, as illustratedherein. The dressing fixture is set to the desired angle of form byrotating the barrel 34. With the dressing tool in the vertical planethrough the axis of the wheel W, feeding movement of the dressing toolmay be accomplished by actuating the cross slide 35, the head 3 beinglowered to cause the tool to engage the wheel.

For straight gash cutters with undercut faces, the setting of thedressing mechanism is the same except that the undercut control member47 is set at an angle of negative rake. The negative rake referred to isnot the undercut angle on the cutter but is the angle to which it isnecessary to dress the grinding wheel to give the proper foreshorteningon the form tool. The angle is a function of the undercut angle on thecutter, the clearance angle on the form tool, the clearance angle on thecutter tooth and the diameter of the cutter. An empirical equation canreadily be set up and by means of a simple calculation, the proper anglefor setting the undercut angle control member 47 may be obtained.

For grinding a straight gash cutter form tool with side clearance thetool blank to be ground is-set at an angle other than the standardclearance angle depending upon the angle of side clearance. The head 126is set at a slight angle to the vertical about the inclined axis of thework holder, this angle corresponding to the angle of side clearance.The tool blank is also swung horizontally at a suflicient angle on thescale 101 to give the proper side clearance angle. The form dressed uponthe grinding wheel is the same as for straight gash cutters, theposition of the tool blank while being ground making provision forobtaining the desired shape on the face of the tool.

In order to grind form tools for straight gash cutters having both sideclearance and undercut faces, the tool blank is set the same as forgrinding form tools with side clearance and the dressing fixture is setthe same as for dressing grinding wheels for cutters with undercutfaces. This combination dressing of the grinding wheel for undercut andpositioning the tool blank for side clearance produces a form tool theface of which is correct for cutting this type of cutter.

To grind tools for spiral gash cutters the tool blank is set at thestandard end clearance angle with the protractors of the work holder setat zero. The head 126 is set at the tip angle corresponding to theclearance and gash angles. In the dressing mechanism the spiral controlmember 45 is set at the angle of the required gash. Since the head 126is tipped the tool blank is 1,979,536 brought to the proper height tocompensate for the spiral gash. v

. When grinding tools for spiral gash cutters with undercut faces thetool blank is set as for spiral gash. cutter tools as just described.The dressing mechanism, in addition to having the spiral control memberset as just described, also has the undercut control member 4'1 set atthe required angle of negative rake.

In grinding form tools for spiral gash cutters with side clearance thehead 126 of the tool holder is set at an angle to the vertical dependingupon whether right or left hand spiral gash as well 'as whether right orleft hand side clearance is desired, after which the tool blank is swunghorizontally about the pivot' 110 through the angle corresponding to therequired side clearance angle. The dressing mechanism is then swiveledon its pivot so that the axis of the barrel 34 is perpendicular to theback of the tool blank and the spiral control member 45 is set parallelwith the face of the tool blank,'the angle 'of which will be either thecombined angles of spiral and side clearance or their difference.

For grinding form tools for spiral gash cutte with both undercut facesand side clearances the to'ol blank is set as described for form toolsfor spiral gash cutters with side clearance.

The dressing mechanism is set as described, and with the undercutcontrol member 47 set at the proper angle.

' d, an arc e. and a second angular. portion or tangent f. Arcs c and'eare struck from two centers kand i, the top a, and land b and thetangent it being taken from the center In while the tangent f is takenfrom the center 1'. Figs. 14 to 18 illustrate diagrammatically thediflerent grindin'g wheels which are dressed to proper form to grind thesix component parts of the *contour of the tool together with the pathsof the dressing tool during the dressing operations.

The grinding wheel W shown in Fig. 14 is adapted to grind the top a onthe tool. This grinding wheel is dressed by setting the radius .slides-70 and'74 opposite the distance m (Fig. 14a) ofthis surface from thecenter k (upwardly in Fig. 3) and with the angle barrel 34 positioned sothat the cross slide 35 moves horizontally, the table 6 is moved so thatthe dressing tool 24 lies in a vertical plane through the axis of thegrinding wheel spindle 4. The grinding wheel head 3 is then lowered tofeed the grinding wheel into engagement with the dressing tool while thecross slide 35 is reciprocated by means of the feed screw to move thedressing tool back and forth across the face of the grinding wheel. Whenthe spindle head 3. has.

been fed downwardly to its final position (the position wherein thewheel W is dressed) the dial upon the micrometer device 17 is set atzero, whereupon the spindle head is raised out of the way.

The tool blankwhicn is mounted in the holder B at the end clearanceangle, is-then moved into operative relation with the grinding wheel bymoving the table by means of the hand wheel 7 12. The work support 23 isthen actuated by means of-the handle 81 so that the work holder istraversed while the spindle head 3 is fed downwardly until the top a' isproperly ground,

whereupon a record is made of the reading of-the' ing parts b and c onthe tool. The dressing. mechanism is now set up using the same center 7cbut changing the ofiset of the radius slides and 74 downwardly onthe-radius bars 38'and 40- to that of the distance n of the land b fromV the center k. A grinding wheelW properly (clockwise looking fromtheleft in Fig- 3) and then reciprocating the dressing tool 24 by meansof the cross slide 35, the head 3 being fed down positioned on thespindle 4 is then dressed along its side by first revolving the anglebarrel 34,

to dress theside of the wheel a suilicient dis-" tance in from theperiphery. j

The head 3 is then withdrawn, the radius slides 'are set central of theshaft 37 and the barr'el 34 is rotated until the dial 99'thereonregisters at an angle 1' (Fig. 150) whereupon the side 2 of the wheel Wis dressed by reciprocating the cross slide 35 while the spindle head 3is fed vertically downward until the micrometer indicates zero. The arcc is dressed on the wheel by first setting the radius slides 70 and 74up- .wardly -(in Fig. 5*) to the radius 3 of the arc, the

cross slide 35 and barrel 34 being then in their central or .zeropositions. The radius bar-is then oscillated (after unlocking the pin66), by meansof the worm and worm wheel control 65 for the sleeve 35,the spindle head 3 being fed downwardly until the dial on the micrometermechanism indicates zero. As the wheel W for grinding the parts b and dis now dressed the head 3 is raised and the table is actuated to bringthe tool blank into operative relation with the wheel. Thenwhile thework holder 23 is traversed'to reciprocate the tool blank across: thegrinding wheel the spindle head is fed down.- wardly until the dial onthe micrometer 17 registers identically with the reading recorded as Ithe position of the head whenzthe top part a ofthe tool was ground.

, As the tangent face d as illustratedrequires a wider wheel, a'wheel Wis properly positioned on the spindle '4. With the radius slides 70 and74 onset the distance D (upwardly in Fig. 3) and the barrel 34 revolved90,-(clockwise, Fig. 7) the wheel W is facedoiI on theright hand side byreciprocating the cross slide 35. Theradius slides are thenoifsetdownwardly. (Fig. 3) the distance a (Fig. 16a) and the barrel 34is revolved (counter-clockwise in Fig. 7) through an angle t from itszero position, whereupon the dressing tool is reciprocated bymeansof-the cross slide 35 while the spindle head is fed downwardly tothe zero point on the micrometer 17.

The radius slides 70 and 74 are then onset again the radius 8 of the arcc after which the barrel is revolved to the angle for dressing the partd which angle is the complement of angle t.' The cross slide 35 is thenreciprocated whfle the wheel W is fed downwardly until the dial on themicrometer mechanism indicates zero. The table is then moved to bringthe tool blank into operative relation with the grinding wheel afterwhich the wheel is fed into the tool blank while the'work the-spindlehead 3)..

support 23 is reciprocated until the dial on the micrometer mechanism 17again indicates the final position of the'head recorded upon cornpletingthe parts, a, b and c of the tool.

Another wheel W is now positioned on the spindle 4 adapted to receivethe proper contour for grinding thearc e. The dressing mechanism is thenadjusted so that the radius slides are offset an amount equal to theradius of the arc e,

the barrel 34 being in its zero position. The wheel is then dressed, thedressing tool being traversed by oscillating the sleeve .36 and thespindle head being fed downwardly. When the spindle head reaches itsfinal position the dial on the micrometer mechanism 17 is'set at zero asthe are e is to be formed on the center i which center is displaced fromthe center is by a horizontal distance 12 and a vertical distance u. Thetool blank must likewise be displaced from its former position through ahorizontal distance 17 (the vertical displacement being taken care of bymovement of The horizontal displacement of the tool blank isaccomplished by means of the work holder B after which the spindle headis fed downwardly while the tool blank is reciprocated until the dial onthe micrometer 17 indicates the former recorded reading minus thedistance u, multiplied by the cosine of the end clearance angle.

The table 6 is again returned to bring the dressing mechanism intooperative relation with the grinding wheel, a difierent grinding wheel Whaving been mounted on.the spindle of sufficient size to grind thetangent surface. 1. The face m (Fig. 18) is dressed on the wheel withthe radius slides set at zero and the barrel 34 positioned at the angleq -(Fig. 14a). The tangent f is likewise dressed on the wheel by firstoffsetting the radius slides to the radius of the are e and positioningthe barrel to an angle complementary to the angle q. When the spindlehead has been fed downwardly and the tangent f dressed on the wheel, thedial of the micrometer is again set at zero. As the tool blank hasalready been offset the horizontal distance v'the tabel is moved tobring the tool blank into operative relation with the grinding wheelwhereupon the blank is reciprocated past the wheel while the head 3 isfed downwardly to the same extent as for the wheel W I 1 I claim as myinvention:

1. A device of the character described comprising, in combination, anoscillatory head, a slidetory inclined guide, a slidable supporttherefor, a ball and socket joint comprising two members,

one being carried by said slide and the other being mounted for radialadjustment on said guide, and means for actuating said support.

3. A device of thecharacter described comprising, in combination, atool, means to support said tool for movement in a plane, a headrotatable about an axis inclined to said plane, means for rotating saidhead, a slidable support for said head, and a universal joint comprisingtwo members, one being connected to said tool and the other beingcarried by said head. i

4. In a device or the character described comprising, in combination,two slides movable in planes at an angle to each other, means to guideone slide in a circular path'in its plane, means to connect said slidescomprising a ball and socket joint and a sliding joint perpendicular tothe plane of movement of the other slide, and a tool operable by one ofsaid slides.

5. A device of the character described comprising, in combination a toolholder,'means to support said tool holder for movement in a plane, andmeans to move said holder through a curved path in said plane, said lastmentioned means including a member rotatable about an axis inclined tosaid plane, and a connection between said member and said holder wherebyupon movement of said member ina circular path about said axis, saidholder moves in a curved path in said plane which is the projection ofsaid circular path on said plane.

6. Means to guide a tool comprising, in'combination, a radiallyextending member pivotally mounted on an axis, a head rotatably mountedon an axis inclined to said first mentioned axis, a tool holder slidablymounted on said head for movement in a plane perpendicular to its axis,a tool carried by said holder, means connecting said tool holder to saidmember comprising a universal joint having one part connected to thetool holder and a complementary part connected to said member, and meansto constrain the pivot point of said universal joint to move in a planeparallel to said head during a rotary movement thereof.

'7. In combination, an abrasive wheel rotatable about its axis, atruing, device adapted to dress said wheel .and movable in an axialplane of said wheel, and means to move said truing device in said planeacross the face of said wheel in an elliptical path, said meanscomprising a head pivotal about an axis perpendicular to said plane, atool holder slidable on said head and carrying said device, a secondhead rotatable about an axis intersecting said first axis; supportingmeans for said second head slidable perpendic-' ularly to said plane,and a universal drive con nection between said tool holder and saidsecond head.

8. Means to guide a tool comprising two heads pivoted on angularlyinclined axes, a part positioned on one head at a predetermined radius,

a second part fiexiblyconnected to said first men-' tioned part andmovable on the other head, said second part being' constrained to travelin a 'plane perpendicularto the axis of its head, and aitool holdermounted on said second part to move parallel therewith during a pivotalmovement of saidheads. 1

- 9. Means to guide a tool comprising, in combination, two membersmounted on axes inclined to each other, a part on one of said membersadjustable radially to a predetermined position with respect to itsaxis, a tool holder on the second of said members freely movable on thememher on a plane perpendicular to its axis, a universal jointconnecting said part to said tool holder, and means to constrainmovement of the point of intersection of said members to a planeperpendicular to the axis of the said second member, thereby to guidethe tool holder in an elliptical path in a plane perpendicular to theaxis of said second member when said first member is rotated about itsaxis.

10. Means to guide a tool comprising, in combination, a pivotal headhaving a radially extending guideway thereon, a rotary head mounted onan axis intersecting the axis of said first head, a tool holder slidablymounted on said guideway, and a connection between said tool holder anda radially extending portion of said rotary head, said connectionincluding means to constrain said radially extending portion frommovement axially of said pivotal head.

11. A device of the character described comprising, in combination, aswingable support.

forming a radial guideway, a slide mounted on saidguideway, a,toolholder rotatably mounted on said slide, and means to guide said toolholder in an elliptical path, said means comprising a radially extendingmember pivotally supported on an axis intersecting the axis of said toolholder, a part adjustable radially on said member, supporting means forsaid member slidable perpendicularly to the plane of said swingablesupport, and rotary drive means connecting said tool holder with saidpart.

12. In combination, an abrasive wheel rotatable about its axis, atruing'device adapted to dress said wheel movable in a planelongitudinally through said axis, and means to move said truing deviceacross the face of said wheel in an elliptical path, said meanscomprising mechanism arranged normally to move said device in anelliptical path and means to modify said path to compensate forundercut.

13. In combination, an abrasive wheel rotatable about its axis, a truingdevice adapted to dress said wheel movable in a plane longitudinallythrough said axis, and means to move said truing device across the faceof said wheel in an elliptical path, said means comprising mechanismarranged normally to move said device in an elliptical path and means tomodify said path to compensate for a'spiral angle. 7

14. A mechanism of the character described comprising, in combination, atool holder, means to support said tool holder for movement in a plane,means to guide said tool holder through an elliptical path in saidplane, and means to control said guide means arranged to modify saidelliptical path to compensate for aspiral angle.

15. A mechanism of the character described comprising, in combination, atool holder, means to support said tool holder for movement in a plane,means to guide said tool holder through an elliptical path in saidplane, means to control said guide means arranged to modify saidelliptical path'to compensate for aspiral angle,

and means to adjust said control means to modify said path to compensatefor undercut.

16.,A dressing mechanism of the character described comprising, incombination, an oscillatory head, a slide thereon, a tool holderrotatably mounted on said slide, an oscillatory guide in- 17. A dressingmechanism comprising, in com-.

bination, an oscillatory head mounted for movement in a plane, a slidethereon, a tool holder movably mounted on said slide, an oscillatoryguide inclined to said head, a. slidable support for said guide movableperpendicularly to said plane,

, a universal joint connection between said guide and tool holder, aninclined oscillatory head, a

slide thereon, a universal joint connection between v said guide andsaid last mentioned slide, and an angularly adjustable support for saidinclined oscillatory head carried on said slidable support.

18-. A dressing mechanism comprising, in combination, an oscillatoryhead mounted for movement in a plane, a tool holder movably mountedthereon, an oscillatory radius bar inclined to said head, a slidablesupport for said bar movable perpendicularly to said plane, a; universaljoint connection between said bar and tool holder, an inclinedoscillatory head, a slide thereon, a universal joint connection betweensaid radius bar and said slide, an angularly adjustable member forsupporting said inclined oscillatory head, and an angularly adjustablecarrier for said member and mounted on said support.

19. A dressing device comprising, in, combination, an oscillatory head,a tool holder movably mounted thereon, an oscillatory head relatively-inclined, to said first mentioned head, a slidable support for one ofsaid heads movable perpendicu alarly to the plane of oscillation of theother of said heads, and a connection between said second mentioned headand said tool holder and embodying means operable during the oscillatorymovement of said second mentioned head to move said slidable support.

20. A dressing device comprising, in combination, an oscillatory head, atool holder movably mounted thereon, an oscillatory head relativelyinclined to said first mentioned head, a slidable support for one ofsaid heads movable perpendicularly to the plane of oscillation of theother of said heads, a connection between said second mentioned head andsaid tool holder and embodying means operable during the oscillatorymovement of said second mentioned head to move said slidable support,and angularly adjustable means arranged to modify the movement of saidsupport.

21. A device of the character described comprising, in combination, anoscillatory head, a tool holder mounted on said head, an oscillatoryhead relatively inclined to said first mentioned head, anangularlyadjustable support for said last mentioned head, a slidablecarrier for said diametrically of said angular support, and a driveconnection between said holder and said last mentioned head.

22. A device of the character described comprising, in combination, asupport, an annular member adjustably mounted on said support on aninclined axis, a slide movable diametrically of said annular member, asleeve rotatably mounted on said slide, a bar slidable longitudinally insaid sleeve, a tool holder, means for supporting said tool'holder fJrmovement in a plane perpendicular to said support, and drive meansconnecting said bar and tool holder. v

23. A device of the character described comprising, in combination, asupport, a base slidable thereon, an annular member adjustably mountedon said base on an inclined axis, a sleeve rotatably mounted in saidmember, a bar slidable longitudinally in said sleeve, 9. tool holder,means for supporting said-tool holder for movement in a planeperpendicular to said support, a part adjustable radially on one endofsaid bar, means connecting said part and tool holder, a second partadjustable radially on the opposite end of said bar, an inclinedoscillatory head adjacent said opposite end of the bar, a slide on saidhead, and means connecting said slide and said second p 7 120 support,means to adjust said last mentioned head 24. A device of the characterdescribed comprising, in combination, a support, a frame slidablethereon, an annular member adjustably mounted on said frame on aninclined axis, a sleeve rotatably mounted on said member, a bar slidablelongitudinally in said sleeve, a tool holder, means for supporting saidtool holder for movement in a plane perpendicular to said support, apart adjustable radially on one end of said bar, means connecting saidpart and tool holder, a second part adjustable radially on the oppositeend of said bar, an inclined oscillatory head adjacent opposite end ofthe bar, a slide on said head, means connecting said slide and saidsecond part, and an angularly adjustable support for said inclinedoscillatory head carried on said frame.

25. A mechanism of the character described comprising, in combination, atool holder, means to support said tool holder for movement in a plane,means available to guide said tool holder through a predetermined pathin said plane, and means to control said last mentioned means to modifysaid path to compensate for side clearance angle.

26. A mechanism of the character described comprising, in combination, atool holder, means to constrain said tool holder for free universalmovement in a plane, means having a guide member movable to define apredetermined projected contour in a plane inclined to said firstmentioned plane, and to move said holder through a path coincident witha projection of said contour in said first mentioned plane foreshortenedto compensate for end clearance angle, and means available to controlsaid last mentioned means to modify the path of said holder.

27. A device of the character described comprising, in combination, asupport, a slide freely reciprocable along a rectilinear path on saidsupport, an annular member mounted on said support for rotary adjustmentabout an axis inclined at an acute angle to said path, a slide mountedfor diametrical adjustment in said member, a

sleeve mounted on said last mentioned slide for rotary afiustment aboutan axis parallel to said first mentioned axis, an elongated barextending axially through said sleeve and being mounted for longitudinaladjustment therein, a rotary tool holder, means mounted on said supportfor constraining said holder for universal movement in a planeperpendicular to said path, and a universal rotary drive connectionbetween one end of said bar and said tool holder and being adjustabletransversely of the axis of said bar selectively into concentricity orinto different degrees of eccentricity with said bar.

'28. In a device of the character described for dressing an abrasivewheel, a support, a tool holder, means on said support for constrainingsaid holder for universal movement in an axial plane of said wheel, andguide means for said holder comprising a slide mounted on said supportfor free floating adjustment in a plane parallel to the axis of saidwheel and perpendicular to said first mentioned plane, a member mountedon said slide for adjustment about an axis perpendicular to said lastmentioned plane, a head mounted on said member for rotary adjustmentabout an axis inclined to said last mentioned plane and having aneccentric part, and a drive connection between said holder and saidpart.

29. In a device of the character described for dressing an abrasivewheel, a support, a tool holder, means on said support for constrainingsaid tool holder for universal movement in an axial plane of said wheel,and guide means for said holder comprising a carrier mounted on saidsupport for free floating adjustment in a plane parallel to the axis ofsaid wheel and perpendicular to said first mentioned plane, a shaftmounted on said carrier for rotary adjustment about an axis inclined tosaid planes and being splined for free floating axial movement, a headon one end of said shaft and having an eccentric part, a driveconnection between said holder and said part, a head on the other end ofsaid shaft and having an eccentric part, a slide, a drive connectionbetween said last mentioned part and said slide, means for constrainingsaid slide for universal movement in a plane fixed relative to saidcarrier, a member for supporting said last mentioned means foradjustment about an axis perpendicular to said shaft and parallel tosaid last mentioned plane, and a member mounted on said carrierforsupporting said last mentioned member for adjustment about an axisperpendicular to said shaft and said last mentioned axis.

JOHN EDGAR.

